X-ray stroboscope offers new insights into biomolecular dynamics

September 10, 2014, Deutsches Elektronen-Synchrotron
Excitation of a stack of lipid membranes by ultra sound leads to collective oscillations which have been probed by time-resolved diffraction. Credit: Tobias Reusch/Tim Salditt, University of Göttingen

Researchers from Göttingen in collaboration with colleagues from Augsburg have 'filmed' the movement of lipid molecules using an X-ray stroboscope at DESY. In the scientific journal Physical Review Letters, researchers lead by Professor Tim Salditt of the University of Göttingen report that their study offers new insights into the dynamics of biomolecules, which compose materials such as cell membranes. The cell membranes consist of a double layer of lipid molecules; the properties of the membranes are of great interest because they control which substances enter and exit a biological cell and also determine which materials are exchanged between different cell regions.

Biomolecules are by nature very mobile. When influenced by heat, they vibrate, turn and stretch. Because these movements constantly overlap, the structure can in most cases be experimentally determined only as an average. "In order to directly track the changes in molecular structure, the spatial resolution must be higher than a millionth of a millimetre and the temporal resolution must be faster than billionth of a second so that the extremely fast movement isn't blurred," explains Salditt.

Both of these conditions are fulfilled by DESY's research light source PETRA III, which provides very bright and short X-ray pulses. Using those pulses, the researchers 'filmed' the motion of a stack of which were externally excited by controlled vibrations using ultrasound. "For the experiment, the membrane vibrations haven been precisely synchronized with the X-ray pulse frequency so that the X-ray flashes captured the movement of the membranes like a stroboscope during different phases," explains DESY scientist Dr. Oliver Seeck, head of the X-ray diffraction experiment P08, where the studies took place. In order to do so, the scientists observed how the X-ray light was scattered on the membranes at different times, thus determining the time-dependent structure.

The researchers observed that the ultrasonic waves not only cause the membranes to vibrate similar to a drumhead, but the microscopic structure is also affected. "Those membranes consisting of molecular lipid bilayers changed both their thickness and their density periodically under the influence of the externally forced motion," said University of Göttingen's Dr. Tobias Reusch, first author of the study. "In order to do so, the molecular lipid chains must collectively stretch and compress, as shown by the density profiles, which we have recorded for each point of oscillation."

"Similar structural changes could also result in membranes of biological cells from temporal fluctuation of forces," explains Salditt. "The visualization of the changes in molecular structure using our stroboscope method makes possible new insights regarding the properties of this 'soft' material."

Explore further: Neutron diffraction sheds light on photosynthesis

More information: "Collective lipid bilayer dynamics excited by surface acoustic waves"; T. Reusch, F. J. R. Schülein, J. D. Nicolas, M. Osterhoff, A. Beerlink, H. J. Krenner, M. Müller, A. Wixforth, and T. Salditt; "Physical Review Letters", 2014; DOI: 10.1103/PhysRevLett.113.118102

Related Stories

Neutron diffraction sheds light on photosynthesis

September 2, 2014

Scientists from ILL and CEA-Grenoble have improved our understanding of the way plants evolved to take advantage of sunlight. Using cold neutron diffraction, they analysed the structure of thylakoid lipids found in plant ...

Nano-forests to reveal secrets of cells

September 2, 2014

Vertical nanowires could be used for detailed studies of what happens on the surface of cells. The findings are important for pharmaceuticals research, among other applications. A group of researchers from Lund University ...

New model of the quality control of photosystem II

June 25, 2014

Thylakoid membranes are piled up to form the grana well known as the site where the Photosystem II (PSII) complexes which play a role in the primary photochemical reaction exist. However, the structures and dynamics of thylakoid ...

Graphene: Potential for modelling cell membrane systems

March 22, 2012

At Toyohashi University of Technology the intriguing properties of graphene—a single atomic-layer of carbon—such as high electron mobility and fluorescence quenching are being exploited for biosensing and analysis ...

Recommended for you

Coffee-based colloids for direct solar absorption

March 22, 2019

Solar energy is one of the most promising resources to help reduce fossil fuel consumption and mitigate greenhouse gas emissions to power a sustainable future. Devices presently in use to convert solar energy into thermal ...

Physicists reveal why matter dominates universe

March 21, 2019

Physicists in the College of Arts and Sciences at Syracuse University have confirmed that matter and antimatter decay differently for elementary particles containing charmed quarks.

ATLAS experiment observes light scattering off light

March 20, 2019

Light-by-light scattering is a very rare phenomenon in which two photons interact, producing another pair of photons. This process was among the earliest predictions of quantum electrodynamics (QED), the quantum theory of ...

How heavy elements come about in the universe

March 19, 2019

Heavy elements are produced during stellar explosion or on the surfaces of neutron stars through the capture of hydrogen nuclei (protons). This occurs at extremely high temperatures, but at relatively low energies. An international ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.